Advanced energy feedstock production can be an eco-friendly means to supplement our growing energy needs by amending the marginal land using biosolids and flue gas desulfurized (FGD) gypsum. Miscanthus giganteus, Switchgrass and Big Bluestem were studied in a RCB design with 2 rates of biosolids (0 and 50 KL/ha) and 2 rates of gypsum (0 and 4 Mg/ha) in split-plot arrangement from 2010 to 2012. Plant height, tiller numbers, biomass production and bioprocessing characteristics were influenced both by gypsum and biosolids. However, the effect of biosolids on growth and yield characteristics of the grasses especially Miscanthus were more pronounced than FGD gypsum. FGD gypsum applied at 4 Mg/ha significantly increased the plant height, tiller numbers (11%), feedstock production (21%) and glucose content (4%) of Miscanthus over the control. Biosolids at 50 KL/ha significantly increased plant heights (29%), tiller numbers (35%), feedstock production (79%), glucose (10%), and total sugar content (3%) over control. Biosolids and gypsum in combination significantly increased the plant heights by up to 31%, tiller numbers up to 42%, feedstock production up to 80%, glucose content up to 13%, and total sugar content up to 6%. Plant macro- and micronutrient nutrients and heavy metals concentration in biofeedstock did not vary significantly in response to FGD gypsum or biosolids. Total and active carbon content increased and soil quality improved when both biosolids and gypsum were applied, but CO₂ emission was slightly higher with only biosolids. Our results suggest that biosolids and FGD gypsum had synergistic effects on biofeedstock production and characteristics of grasses especially Miscanthus when grown in marginal land.